Disposable colorimetric indicator device for measuring the concentration of chlorine in water

ABSTRACT

A disposable plastic syringe contains a measured quantity of a water-soluble colorimetric reagent composition proportioned to the volume of water sample which may be drawn into the syringe. The color produced in the water sample is compared to a chart standard which indicates the concentration of chlorine in the water sample. The measured quantity of the reagent composition is preferably applied as a dried printed spot applied to an inside surface of the syringe device.

United States Patent [1 1 Storm Oct. 30, 1973 DISPOSABLE COLORIMETRICINDICATOR DEVICE FOR MEASURING THE CONCENTRATION OF CHLORINE IN WATER[75] Inventor: Lester F. M. Storm, Glendale, Calif.

[73] Assignee: Sterilizer Control Royalties, North Hollywood, Calif.

22 Filed: Mar. 22, 1971 21 Appl.No.: 126,956

[52] U.S. Cl. 23/253 R, 23/259, 252/408 [51] Int. Cl. G0ln 31/22 [58]Field of Search 23/230, 232, 253,

[56] References Cited UNITED STATES PATENTS 7/1967 Rupe 252/408 11/1971Davis 23/253 TP Rampy 23/253 T? X OTHER PUBLlCATlONS Welcher, F.J.;Organic Analytical Reagents, Vol. IV, p. 473, 1948, QD77W43.

Britton, H.T.S.; Hydrogen Ions, Vol. 1, p. 358, 359, 1943, QD561B7.

Primary ExaminerRobert M. Reese Att0rney--Miner L. Hartmann [57]ABSTRACT A disposable plastic syringe contains a measured quantity of awater-soluble colorimetric reagent composition proportioned to thevolume of water sample which may be drawn into the syringe. The colorproduced in the water sample is compared to a chart standard whichindicates the concentration of chlorine in ,the water sample. Themeasured quantity of the reagent composition is preferably applied as adried printed spot applied to an inside surface of the syringe device.

6 Claims, 6 Drawing Figures DISPOSABLE COLORIMETRIC INDICATOR DEVICE FORMEASURING THE CONCENTRATION OF CI-ILORINE IN WATER BACKGROUND OF THEINVENTION This invention relates to a device for measuring theconcentration of chlorine in water. It is especially applicable for usein regulating the quality of the water in swimming pools, but isapplicable to related uses where it is desirable to know theconcentration of chlorine in water.

SUMMARY OF THE INVENTION In general, the device consists of a disposablesyringe which contains a colorimetric indicator material, preferably indried form, which when dissolved in the water to be tested, produces oneof a number of distinguishable colors. When a given weight of theindicator material is dissolved in a fixed amount of the water to betested, the chlorine content per unit volume is immediately ascertainedby comparison of the colored sample with the colors reproduced on aprinted chart. The preferred device consists of a small disposablesyringe made of transparent plastic. sheet, which contains within itsbulb a tablet or printed spot of the colorimetric reagent, in weightcorresponding to the volume of water sample which will subsequently bedrawn into the syringe. When the water sample is drawn into the syringe,and the device shaken to dissolve the indicator material, the colorproduced measures the chlorine concentration.

The principal object of the invention is to provide an inexpensivedisposable syringe which will draw in a known volume of water to betested and which contains an amount of a wide range colorimetric reagentfor chlorine, which measures the concentration of the chlorine in thedrawn in sample. The colorimetric reagent is selected for its wide rangeof distinguishable colors corresponding to the expected range ofconcentration of chlorine in the water to be tested, for example,swimming pool water.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspectiveview ofone form,of the syringe device;

FIG. 2 is a side elevation view thereof;

FIG. 3 is an elevational view from the inlet tube end of the device;

' FIG. 4 is an elevational view of the end opposite the tube;

FIG. 5 is a top elevational view; and

FIG. 6 is a bottom elevational view. I

The preferred form of syringe for use in this invention is that shown inco-pending application Ser. No. 112,234, now U.S. Pat. No. 3,732,079.Other syringe forms which meet the requirements as set forth may also beemployed.

DESCRIPTION OF A PREFERRED EMBODIMENT This syringe-like device consistsof a rigid base 11, j

which is a plane piece of plastic coated hard cardboard 12 to which aformed plastic bulb l3 imprint is attached (as by heat sealing) at itsoutwardly projecting flanges 14, to form a water holding container orbulb 13. The bulb consists of a rectangular pyramidalshaped sheetplastic body 15 with its walls 16, 17, 18, 19 tapering upwardly andjoined to the walls of a rectangular turret 20 which constitutes thebuttom upon which finger-pressure is applied in the operation of thedevice. The side-walls 21 and 22 of the turret are stiffened by twovertical indented flutes 23. The flutes 23 strengthen the structure ofthe turret so that it moves downwardly as a unit upon applying pressureof the finger, to constrict the total volume of the bulb, and, upon thereleasing of the finger pressure, is restored to its original positionbecause of the inherent resiliency of the synthetic plastic material,for examples, polyvinyl chloride or styrene, of which the device isformed. The sheet thickness 'is preferably in the range of 6 to 10 mils.

An inlet tube 24 connecting the bulb 13 to the outer edge is formed bymolding a rounded groove in the flange 14 adjacent the end wall 16, andthis groove forms a tubular opening when the bulb imprint is sealed tothe base.

A plurality of bulb cavities may be molded from large sheets, andsubsequently be die cut into the individual units before or afterheat-sealing the formed sheet at the flanges between units to theplastic coated cardboard base. Each base sheet before assembly isprinted, flexographically, in spots or stripes which are positioned tobe within the bulb, using a printing ink comprising a color-changeindicator composition for chlorine. The syringe may be used only once,and is then discarded.

The indicator spot 25 or a stripe is printed with a suitable printingink composition. One such composition comprises as its principalcolorimetric ingredient ortho tolidine dihydrochloride, which gives arange of yellow shades corresponding to the chlorine content. Othercolorimetric indicator dyes are triphenyl methane leuco bases,whichproduce colors ranging from yellow to blue to red.

The preferred colorimetric reagent consists of acid fuchsin mixed withortho tolidine dihydrochloride. It has been found that the addition of asmall proportion of potassium bromide improves the brilliance of thecolors produced. The hydrogen ion concentration or pH of the watersample must also be controlled to a range of 3.8 to 4.2 in order for theproper functioning of the colorimetric indicator, and this isaccomplished by adding a buffering agent such as potassium aluminumsulfate.

A preferred ink composition for silk screen printing to produce the spotof reagent on the inside of the plastic syringe, for measuring thechlorine content of the water, is as follows:

Acid Fuchsin 8 parts by weight Ortho tolidine dihydrochloride 40 partsby weight Potassium bromide 750 parts by weight Aluminum PotassiumSulfate 12. H O 1,000 parts by weight Polyvinylpyrrolidone (binder) 183parts by weight Total Solids 1,981 parts by weight Amyl Alcohol(Vehicle) 2,038 parts by weight The consistency of the ink may be variedas required for a chosen printing operation by changing the proportionof the vehicle.

The vehicle evaporates upon the drying of the ink, leaving the otheringredients in the proportions shown.

If the amount of water sample drawn into the syringe device is in therange of 0.9 to 1.1 milliliters, then the weight of the dried ink spotshould be 1.981 milligrams, in order that the colorimetric reagent willbe of the proper concentration to produce the indicative color in thewater sample, as defined by the color chart. The reaction of the colordye combination with the chlorine in the sample is stoichiometric.

The preferred ink composition (after drying off the vehicle) will givethe following standard colors when added to the measured quantity ofwater in the syringe device, as described, and will, for the statedconcentrations of chlorine, yield the identifiable colors as named andnumbered in the following chart:

CHART A Centroid Color lSCC-NBS name and number Light purplish Pink, 249Very light Purple, 221

Very pale Violet, 213

Light Blue, l8]

Light Greenish Blue, 172 Light Bluish Green, 163 Brilliant Green, 140

Very Yellowish Green ll5 Light Olive. I06

Medium Olive Brown, 95 Medium Yellowish Brown, 77 Deep Orange Brown, 69Strong Red Orange, 35

Very Orange, 48

ppM Chlorine I claim: 7

l. A disposable chlorine measuring device for testing water samplescomprising a transparent plastic syringe device having a cavity with oneend open, the other end being closed by a finger-compressibleenlargement, said syringe device containing a dry color-change dyecomposition which is soluble in water, said composition consistingessentially of a mixture of acid fuchsin and orthotolidinedihydrochloride, a water soluble binder, said composition having beenapplied as a printing ink to its inside cavity surface.

2. The device defined in claim 1, in which the composition also containsa pH buffering salt.

3. The device defined in claim 1, in which the composition also containspotassium aluminum sulfate in an amount to control the pH of the watersample to a range of 3.8 to 4.2. I

4. The device defined in claim 1 in which the composition also containsasa'color brightener a water soluble bromide salt.

5. A water soluble composition for colorimetrically measuring theconcentration of chlorine in a sample of water, comprising Acid fuchsin0.8 to parts by weight;

ortho tolidine dihydrochloride 4 to 400 parts by weight;

potassium bromide 375 to 1,500 parts by weight;

aluminum potassium sulfate l2H O 500 to 2,000

parts by weight and a water soluble binder in effective proportion.

6. The composition defined in claim 5 in which said added binder ispolyvinyl pyrrolidone in effective proportion.

2. The device defined in claim 1, in which the composition also containsa pH buffering salt.
 3. The device defined in claim 1, in which thecomposition also contains potassium aluminum sulfate in an amount tocontrol the pH of the water sample to a range of 3.8 to 4.2.
 4. Thedevice defined in claim 1 in which the composition also contains as acolor brightener a water soluble bromide salt.
 5. A water solublecomposition for colorimetrically measuring the concentration of chlorinein a sample of water, comprising Acid fuchsin - 0.8 to 80 parts byweight; ortho tolidine dihydrochloride - 4 to 400 parts by weight;potassium bromide - 375 to 1,500 parts by weight; aluminum potassiumsulfate 12H2O - 500 to 2,000 parts by weight and a water soluble binderin effective proportion.
 6. The composition defined in claim 5 in whichsaid added binder is polyvinyl pyrrolidone in effective proportion.